In general, a semiconductor memory chip utilizes a variety of data output modes such as X16 mode, X32 mode, etc. for inputting and outputting multiple bytes of data with one read or write command. In the X16 mode, 16 bits of data are inputted and outputted at the same time, and, in the X32 mode, 32 bits of data are inputted and outputted at the same time.
FIG. 1 is a diagram illustrating a conventional semiconductor memory chip configuration.
The conventional semiconductor memory chip in FIG. 1 includes a first pad unit 11, a second pad unit 12, a third pad unit 13, and a fourth pad unit 14. The first pad unit 11 includes first to eighth data pads DQ<1:8>, a first data strobe pad DS<1>, and a first data mask pad DM<1>. The second pad unit 12 includes ninth to 16th data pads DQ<9:16>, a second data strobe pad DS<2>, and a second data mask pad DM<2>. The third pad unit 13 includes 17th to 24th data pads DQ<17:24>, a third data strobe pad DS<3>, and a third data mask pad DM<3>. The fourth pad unit 14 includes 25th to 32nd data pads DQ<25:32>, a fourth data strobe pad DS<4>, and a fourth data mask pad DM<4>.
A conventional semiconductor memory chip configured in such a manner would utilize some or all of the first to fourth pad units 11 to 14 to input and output data according to a data input/output mode in effect. For example, the standards of Joint Electron Device Engineering Council (JEDEC) specify that data are to be inputted and outputted through the first to fourth pad units 11 to 14 in the X32 mode or through the second and third pad units 12 and 13 in the X16 mode.
With the development of the semiconductor industry, electronic devices have been miniaturized for reduction in size and weight. Multi-chip packaging is one of the techniques used for miniaturizing electronic devices. A multi-chip package is a package formed by mounting a plurality of semiconductor memory chips on a lead frame. Multi-chip packaging is frequently used to reduce the mounting area and the weight of, for example, mobile devices such as mobile phones or the like.
FIG. 2 is a diagram illustrating a multi-chip package configuration using the conventional semiconductor chip illustrated in FIG. 1.
Referring to FIG. 2, the multi-chip package 15 includes a first semiconductor chip 16 and a second semiconductor chip 17. In order to implement the multi-chip package 15 operating in the X32 mode, both the first and second semiconductor chips 16 and 17 operate in the X16 mode. Therefore, a pad unit 161 of the first semiconductor chip 16 and a pad unit 171 of the second semiconductor chip 17 should be bonded to a pad unit 151 of the multi-chip package 15.
When the first and second semiconductor memory chips 16 and 17 operate in the X16 mode, data are inputted and outputted through a pad unit positioned in the center of the first and second semiconductor chips 16 and 17. Accordingly, it can be seen that coupling the pad unit 161 of the first semiconductor memory chip 16 to the pad unit 151 of the multi-chip package 15 may create difficulties in packaging. Furthermore, different loading difference will also occur between the signals transferred through the bonding wires coupling the pad unit 161 of the first semiconductor memory chip 16 to the pad unit 151 of the multi-chip package 15 and the signals transferred through the bonding wires coupling the pad unit 171 of the second semiconductor memory chip 17 to the pad unit 151 of the multi-chip package 15.